Turn on server rendering

The rails/wepbacker default setup does not work with hot or live reloading, yet, per Webpacker issue #842. If you want the combination of both server rendering and hot reloading during development, you will need to a custom webpack setup as shown here

Edit app/views/hello_world/index.html.erb and set prerender to true.

Refresh the page.

This is the line where you turn server rendering on by setting prerender to true:

If any of this resonates with you, please email me, justin@shakacode.com. I offer a free half-hour project consultation, on anything from React on Rails to any aspect of web or mobile application development for both consumer and enterprise products.

Community

Please click to subscribe to keep in touch with Justin Gordon and ShakaCode. I intend to send announcements of new releases of React on Rails and of our latest blog articles and tutorials. Subscribers will also have access to exclusive content, including tips and examples.

Slack Room: Contact us for an invite to the ShakaCode Slack room! Let us know if you want to contribute.

React on Rails

Project Objective: To provide an opinionated and optimal framework for integrating Ruby on Rails with React via the Webpacker gem.

React on Rails integrates Facebook's React front-end framework with Rails. React v0.14.x and greater is supported, with server rendering. Redux and React-Router are supported as well, also with server rendering, using execJS.

Features

Like the react-rails gem, React on Rails is capable of server-side rendering with fragment caching and is compatible with turbolinks. While the initial setup is slightly more involved, it allows for advanced functionality such as:

This usage of webpack fits neatly and simply into existing Rails apps. You can include React components on a Rails view with a simple helper.

Compare this to some alternative approaches for SPAs (Single Page Apps) that utilize Webpack and Rails. They will use a separate node server to distribute web pages, JavaScript assets, CSS, etc., and will still use Rails as an API server. A good example of this is our ShakaCode team member Alex's article
Universal React with Rails: Part I.

Webpack Configuration: custom setup for Webpack or rails/webpacker?

Version 9 of React on Rails added support for the rails/webpacker view helpers so that Webpack produced assets would no longer pass through the Rails asset pipeline. As part of this change, React on Rails added a configuration option to support customization of the node_modules directory. This allowed React on Rails to support the rails/webpacker configuration of the Webpack configuration.

A key decision in your use React on Rails is whether you go with the rails/webpacker default setup or the traditional React on Rails setup of putting all your client side files under the /client directory. While there are technically 2 independent choices involved, the directory structure and the mechanism of Webpack configuration, for simplicity sake we'll assume that these choices go together.

Traditional React on Rails using the /client directory

Until version 9, all React on Rails apps used the /client directory for configuring React on Rails in terms of the configuration of Webpack and location of your JavaScript and Webpack files, including the node_modules directory. Version 9 changed the default to / for the node_modules location using this value in config/initializers/react_on_rails.rb: config.node_modules_location.

The ShakaCode Teamrecommends this approach for projects beyond the simplest cases as it provides the greatest transparency in your webpack and overall client-side setup. The big advantage to this is that almost everything within the /client directory will apply if you wish to convert your client-side code to a pure Single Page Application that runs without Rails. This allows you to google for how to do something with Webpack configuration and what applies to a non-Rails app will apply just as well to a React on Rails app.

In this case, you don't need to understand the nuances of customization of your Wepback config via the Webpacker mechanism.

rails/webpacker Setup

Typical rails/webpacker apps have a standard directory structure as documented here. If you follow the steps in the the basic tutorial, you will see this pattern in action. In order to customize the Webpack configuration, you need to consult with the rails/webpacker Webpack configuration.

Version 9 made this the default for generated apps for 2 reasons:

It's less code to generate and thus less to explain.

rails/webpacker might be viewed as a convention in the Rails community.

The advantage of this is that there is very little code needed to get started and you don't need to understand really anything about Webpack customization. The big disadvantage to this is that you will need to learn the ins and outs of the [rails/webpacker way to customize Webpack](Webpacker mechanism) (not the plain Webpack way) if you wish to beyond the basic setup, and this sort of knowledge is not going to be particularly applicable if you eventually want to convert your client-side app to a pure Single Page Application that runs without rails.

Overall, consider carefully if you prefer the rails/webpacker directory structure and Webpack configuration, over the placement of all client side files within the /client directory along with conventional Webpack configuration.

Getting Started with an existing Rails app

Add the following to your Gemfile and bundle install. We recommend fixing the version of React on Rails, as you will need to keep the exact version in sync with the version in your client/package.json file.

Commit this to git (or else you cannot run the generator unless you pass the option --ignore-warnings).

See help for the generator:

rails generate react_on_rails:install --help

Run the generator with a simple "Hello World" example (more options below):

rails generate react_on_rails:install

Ensure that you have foreman installed: gem install foreman.

Start your Rails server:

foreman start -f Procfile.dev

Visit localhost:3000/hello_world. Note: foreman defaults to PORT 5000 unless you set the value of PORT in your environment. For example, you can export PORT=3000 to use the Rails default port of 3000. For the hello_world example this is already set.

Installation Overview

Initializer Configuration

Configure the config/initializers/react_on_rails.rb. You can adjust some necessary settings and defaults. See file spec/dummy/config/initializers/react_on_rails.rb for a detailed example of configuration, including comments on the different values to configure.

Including your React Component in your Rails Views

Normal Mode (React component will be rendered on client):

<%= react_component("HelloWorld",props:@some_props)%>

Server-Side Rendering (React component is first rendered into HTML on the server):

<%= react_component("HelloWorld",props:@some_props,prerender:true)%>

The component_name parameter is a string matching the name you used to expose your React component globally. So, in the above examples, if you had a React component named "HelloWorld", you would register it with the following lines:

importReactOnRailsfrom'react-on-rails';

importHelloWorldfrom'./HelloWorld';

ReactOnRails.register({ HelloWorld });

Exposing your component in this way is how React on Rails is able to reference your component from a Rails view. You can expose as many components as you like, as long as their names do not collide. See below for the details of how you expose your components via the react_on_rails webpack configuration.

@some_props can be either a hash or JSON string. This is an optional argument assuming you do not need to pass any options (if you want to pass options, such as prerender: true, but you do not want to pass any properties, simply pass an empty hash {}). This will make the data available in your component:

Convert rails-5 API only app to rails app

Go to the directory where you created your app

rails new your-current-app-name

Rails will start creating the app and will skip the files you have already created. If there is some conflict then it will stop and you need to resolve it manually. be careful at this step as it might replace you current code in conflicted files.

Resolve conflicts

1. Press "d" to see the difference
2. If it is only adding lines then press "y" to continue
3. If it is removeing some of your code then press "n" and add all additions manually

NPM

All JavaScript in React On Rails is loaded from npm: react-on-rails. To manually install this (you did not use the generator), assuming you have a standard configuration, run this command (assuming you are in the directory where you have your node_modules):

yarn add react-on-rails

That will install the latest version and update your package.json.

Webpacker Configuration

React on Rails users should set configuration value compile to false, as React on Rails handles compilation for test and production environments.

How it Works

The generator installs your webpack files in the client folder. Foreman uses webpack to compile your code and output the bundled results to app/assets/webpack, which are then loaded by sprockets. These generated bundle files have been added to your .gitignore for your convenience.

Inside your Rails views, you can now use the react_component helper method provided by React on Rails. You can pass props directly to the react component helper. You can also initialize a Redux store with view or controller helper redux_store so that the store can be shared amongst multiple React components. See the docs for redux_store below and scan the code inside of the /spec/dummy sample app.

Client-Side Rendering vs. Server-Side Rendering

In most cases, you should use the prerender: false (default behavior) with the provided helper method to render the React component from your Rails views. In some cases, such as when SEO is vital, or many users will not have JavaScript enabled, you can enable server-rendering by passing prerender: true to your helper, or you can simply change the default in config/initializers/react_on_rails.

Now the server will interpret your JavaScript using ExecJS and pass the resulting HTML to the client. We recommend using mini_racer as ExecJS's runtime. The generator will automatically add it to your Gemfile for you (once we complete #501).

In the following screenshot you can see the 3 parts of React on Rails rendering:

A hidden HTML div contains the properties of the React component, such as the registered name and any props. A JavaScript function runs after the page loads to take this data and build initialize React components.

The wrapper div <div id="HelloWorld-react-component-0"> specifies the div where to place the React rendering. It encloses the server-rendered HTML for the React component

Additional JavaScript is placed to console-log any messages, such as server rendering errors. Note: these server side logs can be configured only to be sent to the server logs.

Note:

If server rendering is not used (prerender: false), then the major difference is that the HTML rendered for the React component only contains the outer div: <div id="HelloWorld-react-component-0"/>. The first specification of the React component is just the same.

The below image is not yet updated for version 7.0.0 which uses a <script> tag for the props. Instead of a hidden div, we have the props inside of the <script> tag.

Building the Bundles

Each time you change your client code, you will need to re-generate the bundles (the webpack-created JavaScript files included in application.js). The included Foreman Procfile.dev will take care of this for you by watching your JavaScript code files for changes. Simply run foreman start -f Procfile.dev.

On production deployments that use asset precompilation, such as Heroku deployments, React on Rails, by default, will automatically run webpack to build your JavaScript bundles. You can see the source code for what gets added to your precompilation here. For more information on this topic, see the doc on Heroku deployment.

If you have used the provided generator, these bundles will automatically be added to your .gitignore to prevent extraneous noise from re-generated code in your pull requests. You will want to do this manually if you do not use the provided generator.

Generator Functions

Why would you create a function that returns a React component rather than simply an Object that is a React class?

You need access to the railsContext. See documentation for the railsContext in terms of why you might need it. You need a generator function to access the railsContext.

You may want the ability to use the passed-in props to initialize a redux store or set up react-router

You may want to return different components depending on what's in the props.

ReactOnRails will automatically detect a registered generator function. Thus, there is no difference between registering a React Component versus a "generator function."

Another reason to use a generator function is that sometimes in server rendering, specifically with React Router, you need to return the result of calling ReactDOMServer.renderToString(element). You can do this by returning an object with the following shape: { renderedHtml, redirectLocation, error }.

For server rendering, if you wish to return multiple HTML strings from a generator function, you may return an Object from your generator function with a single top level property of renderedHtml. Inside this Object, place a key called componentHtml, along with any other needed keys. An example scenario of this is when you are using side effects libraries like React Helmet. Your Ruby code will get this Object as a Hash containing keys componentHtml and any other custom keys that you added:
{ renderedHtml: { componentHtml, customKey1, customKey2} }

Note: The functionality in the above paragraph requires the use of our new react_component_hash method. Said functionality in our react_component method is now deprecated.

Rails Context and Generator Functions

When you use a "generator function" to create react components (or renderedHtml on the server), or you used shared redux stores, you get two params passed to your function that creates a React component:

props: Props that you pass in the view helper of either react_component or redux_store

railsContext: Rails contextual information, such as the current pathname. You can customize this in your config file. Note: The railsContext is not related to the concept of a "context" for React components.

This parameters (props and railsContext) will be the same regardless of either client or server side rendering, except for the key serverSide based on whether or not you are server rendering.

While you could manually configure your Rails code to pass the "railsContext information" with the rest of your "props", the railsContext is a convenience because it's passed consistently to all invocations of generator functions.

For example, suppose you create a "generator function" called MyAppComponent.

importReactfrom'react';

constMyAppComponent=(props,railsContext)=>(

<div>

<p>props are:{JSON.stringify(props)}</p>

<p>railsContext is:{JSON.stringify(railsContext)}

</p>

</div>

);

exportdefaultMyAppComponent;

Note: you will get a React browser console warning if you try to serverRender this since the value of serverSide will be different for server rendering.

So if you register your generator function MyAppComponent, it will get called like:

reactComponent =MyAppComponent(props, railsContext);

and, similarly, any redux store always initialized with 2 parameters:

reduxStore =MyReduxStore(props, railsContext);

Note: you never make these calls. React on Rails makes these calls when it does either client or server rendering. You will define functions that take these 2 params and return a React component or a Redux Store. Naturally, you do not have to use second parameter of the railsContext if you do not need it.

(Note: see below section on how to setup redux stores that allow multiple components to talk to the same store.)

serverSide: boolean # Are we being called on the server or client? Note: if you conditionally

# render something different on the server than the client, then React will only show the

# server version!

}

Why the railsContext is only passed to generator functions

There's no reason that the railsContext would ever get passed to your React component unless the value is explicitly put into the props used for rendering. If you create a react component, rather than a generator function, for use by React on Rails, then you get whatever props are passed in from the view helper, which does not include the Rails Context. It's trivial to wrap your component in a "generator function" to return a new component that takes both:

Use Cases

Needing the current URL path for server rendering

Suppose you want to display a nav bar with the current navigation link highlighted by the URL. When you server-render the code, your code will need to know the current URL/path. The new railsContext has this information. Your application will apply something like an "active" class on the server rendering.

Configuring different code for server side rendering

Suppose you want to turn off animation when doing server side rendering. The serverSide value is just what you need.

Customization of the rails_context

You can customize the values passed in the railsContext in your config/initializers/react_on_rails.rb. Here's how.

Set the config value for the rendering_extension:

config.rendering_extension =RenderingExtension

Implement it like this above in the same file. Create a class method on the module called custom_context that takes the view_context for a param.

# Return a Hash that contains custom values from the view context that will get merged with

# the standard rails_context values and passed to all calls to generator functions used by the

# react_component and redux_store view helpers

defself.custom_context(view_context)

{

somethingUseful: view_context.session[:something_useful]

}

end

end

In this case, a prop and value for somethingUseful will go into the railsContext passed to all react_component and redux_store calls. You may set any values available in the view rendering context.

Globally Exposing Your React Components

Place your JavaScript code inside of the default app/javascript folder. Use modules just as you would when using webpack alone. The difference here is that instead of mounting React components directly to an element using React.render, you register your components to ReactOnRails and then mount them with helpers inside of your Rails views.

This is how to expose a component to the react_component view helper.

// app/javascript/packs/hello-world-bundle.js

importHelloWorldfrom'../components/HelloWorld';

importReactOnRailsfrom'react-on-rails';

ReactOnRails.register({ HelloWorld });

Different Server-Side Rendering Code (and a Server Specific Bundle)

You may want different initialization for your server-rendered components. For example, if you have an animation that runs when a component is displayed, you might need to turn that off when server rendering. However, the railsContext will tell you if your JavaScript code is running client side or server side. So code that required a different server bundle previously may no longer require this!

If you want different code to run, you'd set up a separate webpack compilation file and you'd specify a different, server side entry file. ex. 'serverHelloWorld.jsx'. Note: you might be initializing HelloWorld with version specialized for server rendering.

Renderer Functions

A renderer function is a generator function that accepts three arguments: (props, railsContext, domNodeId) => { ... }. Instead of returning a React component, a renderer is responsible for calling ReactDOM.render to render a React component into the dom. Why would you want to call ReactDOM.render yourself? One possible use case is code splitting.

Renderer functions are not meant to be used on the server since there's no DOM on the server. Instead, use a generator function. Attempting to server render with a renderer function will cause an error.

ReactOnRails View Helpers API

Once the bundled files have been generated in your app/assets/webpack folder and you have registered your components, you will want to render these components on your Rails views using the included helper method, react_component.

react_component

react_component(component_name,

props:{},

prerender:nil,

trace:nil,

replay_console:nil,

raise_on_prerender_error:nil,

id:nil,

html_options:{})

component_name: Can be a React component, created using an ES6 class or a generator function that returns a React component (or, only on the server side, an object with shape { redirectLocation, error, renderedHtml }), or a "renderer function" that manually renders a React component to the dom (client side only).

options:

props: Ruby Hash which contains the properties to pass to the react object, or a JSON string. If you pass a string, we'll escape it for you.

prerender: enable server-side rendering of a component. Set to false when debugging!

id: Id for the div, will be used to attach the React component. This will get assigned automatically if you do not provide an id. Must be unique.

html_options: Any other HTML options get placed on the added div for the component. For example, you can set a class (or inline style) on the outer div so that it behaves like a span, with the styling of display:inline-block.

trace: set to true to print additional debugging information in the browser. Defaults to true for development, off otherwise. Note: on the client, you will see both the railsContext and your props. On the server, you only see the railsContext being logged.

replay_console: Default is true. False will disable echoing server-rendering logs to the browser. While this can make troubleshooting server rendering difficult, so long as you have the default configuration of logging_on_server set to true, you'll still see the errors on the server.

raise_on_prerender_error: Default is false. True will throw an error on the server side rendering. Your controller will have to handle the error.

redux_store

Controller Extension

Include the module ReactOnRails::Controller in your controller, probably in ApplicationController. This will provide the following controller method, which you can call in your controller actions:

redux_store(store_name, props: {})

store_name: A name for the store. You'll refer to this name in 2 places in your JavaScript:

You'll call ReactOnRails.registerStore({storeName}) in the same place that you register your components.

In your component definition, you'll call ReactOnRails.getStore('storeName') to get the hydrated Redux store to attach to your components.

props: Named parameter props. ReactOnRails takes care of setting up the hydration of your store with props from the view.

View Helper

redux_store(store_name, props: {})

This method has the same API as the controller extension. HOWEVER, we recommend the controller extension instead because the Rails executes the template code in the controller action's view file (erb, haml, slim, etc.) before the layout. So long as you call redux_store at the beginning of your action's view file, this will work. However, it's an easy mistake to put this call in the wrong place. Calling redux_store in the controller action ensures proper load order, regardless of where you call this in the controller action. Note: you won't know of this subtle ordering issue until you server render and you find that your store is not hydrated properly.

redux_store_hydration_data

Place this view helper (no parameters) at the end of your shared layout so ReactOnRails will render the redux store hydration data. Since we're going to be setting up the stores in the controllers, we need to know where on the view to put the client-side rendering of this hydration data, which is a hidden div with a matching class that contains a data props. For an example, see spec/dummy/app/views/layouts/application.html.erb.

Redux Store Notes

Note: you don't need to initialize your redux store. You can pass the props to your React component in a "generator function." However, consider using the redux_store helper for the two following use cases:

You want to have multiple React components accessing the same store at once.

You want to place the props to hydrate the client side stores at the very end of your HTML so that the browser can render all earlier HTML first. This is particularly useful if your props will be large.

server_render_js

server_render_js(js_expression, options = {})

js_expression, like 2 + 3, and not a block of js code. If you have more than one line that needs to be executed, wrap it in an IIFE. JS exceptions will be caught, and console messages will be handled properly

Currently, the only option you may pass is replay_console (boolean)

This is a helper method that takes any JavaScript expression and returns the output from evaluating it. If you have more than one line that needs to be executed, wrap it in an IIFE. JS exceptions will be caught and console messages handled properly.

Multiple React Components on a Page with One Store

You may wish to have 2 React components share the same the Redux store. For example, if your navbar is a React component, you may want it to use the same store as your component in the main area of the page. You may even want multiple React components in the main area, which allows for greater modularity. Also, you may want this to work with Turbolinks to minimize reloading the JavaScript. A good example of this would be something like a notifications counter in a header. As each notification is read in the body of the page, you would like to update the header. If both the header and body share the same Redux store, then this is trivial. Otherwise, we have to rely on other solutions, such as the header polling the server to see how many unread notifications exist.

Suppose the Redux store is called appStore, and you have 3 React components that each needs to connect to a store: NavbarApp, CommentsApp, and BlogsApp. I named them with App to indicate that they are the registered components.

You will need to make a function that can create the store you will be using for all components and register it via the registerStore method. Note: this is a storeCreator, meaning that it is a function that takes (props, location) and returns a store:

functionappStore(props,railsContext){

// Create a hydrated redux store, using props and the railsContext (object with

// Rails contextual information).

return myAppStore;

}

ReactOnRails.registerStore({

appStore

});

When registering your component with React on Rails, you can get the store via ReactOnRails.getStore:

// getStore will initialize the store if not already initialized, so creates or retrieves store

constappStore=ReactOnRails.getStore("appStore");

return(

<Provider store={appStore}>

<CommentsApp />

</Provider>

);

From your Rails view, you can use the provided helper redux_store(store_name, props) to create a fresh version of the store (because it may already exist if you came from visiting a previous page). Note: for this example, since we're initializing this from the main layout, we're using a generic name of @react_props. In other words, the Rails controller would set @react_props to the properties to hydrate the Redux store.

app/views/layouts/application.html.erb

...

<%= redux_store("appStore",props:@react_props)%>;

<%= react_component("NavbarApp")%>

yield

...

Components are created as stateless function(al) components. Since you can pass in initial props via the helper redux_store, you do not need to pass any props directly to the component. Instead, the component hydrates by connecting to the store.

_comments.html.erb

<%= react_component("CommentsApp")%>

_blogs.html.erb

<%= react_component("BlogsApp")%>

Note: You will not be doing any partial updates to the Redux store when loading a new page. When the page content loads, React on Rails will rehydrate a new version of the store with whatever props are placed on the page.

ReactOnRails JavaScript API

Using Rails built-in CSRF protection in JavaScript

Rails has built-in protection for Cross-Site Request Forgery (CSRF), see Rails Documentation. To nicely utilize this feature in JavaScript requests, React on Rails provides two helpers that can be used as following for POST, PUT or DELETE requests:

Code Splitting docs for information about how to set up code splitting for server rendered routes.

Caching and Performance

Consider fragment and http caching of pages that contain React on Rails components. See Caching and Performance for more details.

Deployment

React on Rails puts the necessary precompile steps automatically in the rake precompile step. You can, however, disable this by setting certain values to nil in the config/initializers/react_on_rails.rb.

config.symlink_non_digested_assets_regex: Set to nil to turn off the setup of non-js assets.

build_production_command: Set to nil to turn off the precompilation of the js assets.

See the Heroku Deployment doc for specifics regarding Heroku. The information here should apply to other deployments.

Integration with Node.js for Server Rendering

If you want to use a node server for server rendering, get in touch. ShakaCode has built a premium Node rendering server for React on Rails.

Dependencies

Rails 3.2 will work and is tested up to 6.8.x. We are not testing it for new releases. If you find an issue, you will have to submit a PR to get it fixed.

Node 5.5 or greater

Contributing

Bug reports and pull requests are welcome. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to our version of the Contributor Covenant Code of Conduct).

Please Subscribe to keep in touch with Justin Gordon and ShakaCode. I intend to send announcements of new releases of React on Rails and of our latest blog articles and tutorials. Subscribers will also have access to exclusive content, including tips and examples.

If any of this resonates with you, please email me, justin@shakacode.com. I offer a free half-hour project consultation, on anything from React on Rails to any aspect of web or mobile application development for both consumer and enterprise products.